Clay colored stool means little or no bile is reaching your intestine, so your stool loses the pigment that normally turns it brown.[1][2] The usual causes are a blocked bile duct, liver inflammation, some medicines and fat malabsorption.[1][3] Pale stool that lasts more than a few days, or comes with yellow skin or dark urine, needs a clinician's assessment.[1]
This guide explains how bile colors stool, what can interrupt it, where the gut microbiome fits in, how doctors find the cause, and what to do while you wait. It is written for adults; one short section covers babies, where pale stool is more urgent.
Get medical help promptly if pale stool comes with yellowing of the skin or eyes, dark urine, itching, or right upper abdominal pain with fever. These can signal a blocked bile duct, liver inflammation or a bile duct infection (cholangitis) and need a clinician, not home care.[4]
Why does bile give stool its brown color?
Stool is brown because of bile pigment. Your liver conjugates bilirubin, a breakdown product of old red blood cells, and secretes it into bile.[2] Gut bacteria then convert bilirubin to urobilinogen, and compounds oxidized from it, urobilin and stercobilin, form the dark pigment of feces.[2]
If bile cannot reach the intestine, that pigment never forms. The result is stool that looks pale, gray, white or putty-colored.[1][4] It is the same chemistry behind jaundice: bilirubin that cannot leave through the gut builds up in the blood and shows in the skin and urine.[1][4]
What causes clay colored stool?
Pale stool is a sign of a bile-flow problem somewhere between the liver and the small intestine. MedlinePlus lists the causes below, and a StatPearls chapter on biliary obstruction adds the detail on benign versus cancerous blockages.[1][4]
| Cause | What happens | Clues that often come with it |
|---|---|---|
| Gallstones in the bile duct | A stone lodges in the common bile duct and blocks bile. An ASGE guideline notes this can lead to biliary obstruction, cholangitis and pancreatitis.[5] | Jaundice, dark urine; fever and right upper pain suggest infection[4] |
| Bile duct strictures or cysts | Narrowing or cysts in the ducts, some present from birth, restrict flow.[1] | Jaundice, itching[4] |
| Tumors of the bile duct, pancreas or liver | Cholangiocarcinoma or pancreatic head cancer can narrow the common bile duct.[4] | Jaundice, itching[4] |
| Viral or alcoholic hepatitis | Inflamed liver cells make less bile or release it poorly.[1] | Jaundice, dark urine[1] |
| Biliary cirrhosis or sclerosing cholangitis | Chronic scarring or inflammation of the bile ducts.[1] | Found on liver tests and imaging |
| Some medicines and supplements | Cholestatic drug-induced liver injury.[6] | A recent new medicine or supplement |
Can liver disease cause clay colored stool?
Yes, when liver disease reduces bile production or blocks its flow.[1] Hepatitis A shows how common the pattern is: StatPearls reports jaundice in 40% to 80% of cases, dark urine in 68% to 94%, and cholestatic symptoms including acholic stools in about half of patients.[7] The acute illness typically resolves within two months, and a prolonged cholestatic form affects fewer than 5% of patients.[7]
Does fatty liver turn stool pale?
Rarely, if ever, on its own. The AASLD practice guidance says that in most patients nonalcoholic fatty liver disease is asymptomatic or causes only vague symptoms.[8] So pale stool in someone with fatty liver is not explained by the fat alone, and it is worth raising with a clinician to look for a second problem such as a gallstone.
Can medicines or supplements cause pale stool?
They can, through cholestatic drug-induced liver injury. In the Western world the drug classes most often behind idiosyncratic liver injury are antimicrobials, herbal and dietary supplements, and anticancer drugs, and the injury can present as cholestatic jaundice.[6] A 2024 review adds that several herbal and dietary supplements have recently been linked to cholestatic liver injury.[9]
Drug injury is a diagnosis of exclusion, so clinicians first rule out gallstones, tumors and viral hepatitis.[6][9] If your stool turns pale after starting something new, do not stop a prescribed medicine on your own. Call the prescriber or pharmacist and bring a full list of medicines and supplements to the visit.
Can food make stool pale or clay-colored?
Not in the sources we read. MedlinePlus's list of causes for clay-colored stool contains liver and bile-duct disease, tumors, gallstones and some medicines, and no foods.[1] A stool that is merely lighter brown after a meal is a different finding from the putty-colored stool of missing bile pigment. Pale, bulky stool from excess fat is a malabsorption sign, not a food effect, and it persists on a normal diet.[3] For a general guide to colors and shapes, see the Bristol stool chart guide.
Is pale, greasy stool bile or fat malabsorption?
They overlap, but they are not the same. Stool that carries excess fat becomes pale, large in volume and foul-smelling, a pattern called steatorrhea, defined as more than 7 grams of fat in the stool over 24 hours.[3] StatPearls lists three groups of causes: exocrine pancreatic insufficiency, bile acid deficiency states and diseases of the small intestine.[3]
The AGA lists the features of pancreatic enzyme shortage as steatorrhea with or without diarrhea, weight loss, bloating, excessive gas and fat-soluble vitamin deficiencies.[10] It advises considering it in people with celiac disease or Crohn's disease, and names a fecal elastase below 100 µg/g of stool as good evidence of the problem.[10] Clay-colored stool from a bile-flow problem, by contrast, is typically paired with jaundice and dark urine.[1] For other loose-stool patterns, see our guide to diarrhea.
What does the gut microbiome have to do with stool color?
Gut bacteria finish the job that makes stool brown. A 2024 Nature Microbiology study identified BilR, a bacterial enzyme that reduces bilirubin to urobilinogen, and found it is encoded mainly by Firmicutes.[11] The gene is nearly ubiquitous in the gut metagenomes of healthy adults but less common in neonates and in people with inflammatory bowel disease.[11] That was an analysis of gene prevalence, not of stool color, so it does not show that low BilR causes pale stool. Two researchers writing in Trends in Molecular Medicine call the discovery a major step in linking the microbiota to bilirubin metabolism.[12]
The microbiome also reshapes bile itself. Bacteria dehydroxylate the liver's primary bile acids into deoxycholic and lithocholic acid,[2] and a 2023 review notes that antibiotics and diet shape the composition of the bile acid pool.[13] Our page on secondary bile acids covers what these molecules do, and balanced bile acid metabolism covers the wider picture. Other bile acids, such as ursodeoxycholic acid, have their own pages.
None of this makes clay colored stool a microbiome problem to fix with a probiotic. Pale stool from a blocked duct is a plumbing problem, and treatment targets the blockage; for stones in the bile duct, the primary treatment is endoscopic (ERCP).[5]
Is clay colored stool different in babies?
Yes, and it is more urgent. Cholestatic jaundice affects about 1 in 2,500 term infants, and biliary atresia accounts for 25% to 40% of cases.[14] A joint NASPGHAN and ESPGHAN guideline says any infant who is jaundiced after 2 weeks of age should be evaluated for cholestasis with total and direct bilirubin.[14]
Stool color cards help parents notice. In Taiwan, a national stool color card program was associated with a fall in very late referrals for suspected biliary atresia, from 9.5% to 4.9%.[15] If a baby's stool is pale or clay-colored, contact the pediatrician promptly.
How do doctors find the cause?
They start with questions: when the change began, whether every stool is pale, which medicines you take and what other symptoms you have.[1] Then come blood tests and imaging.
- Blood tests: liver function tests and viral hepatitis tests, including fractionated bilirubin and alkaline phosphatase.[1][4]
- Abdominal ultrasound: a low-cost, noninvasive first imaging test that shows gallstones and dilated bile ducts.[4]
- MRCP, CT or MRI: MRCP is very sensitive for strictures, stones and tumors in the ducts.[4][1]
- ERCP: an endoscopic procedure that can both diagnose and treat a blockage.[1][5]
What can you do while you wait for an appointment?
- Note the date it started and whether every stool is pale or only some.
- Check your urine color and the whites of your eyes in daylight; dark urine and yellowing often accompany clay-colored stool.[1]
- List every medicine and supplement, including herbal products, with start dates.[6]
- Take a photo of the stool in good light to show the clinician.
- Skip "liver cleanse" products and do not stop prescribed medicines without advice.
When should you see a doctor?
Contact a health care provider if your stools are not their normal brown color for several days.[1] Seek care the same day for pale stool with any of these:
- Yellow skin or eyes, or dark urine.[1]
- Itching without a rash, which is common in biliary obstruction.[4]
Go to an emergency department for pale stool with right upper abdominal pain, fever and jaundice (Charcot's triad), or if confusion or shock appears.[4] For a different color change, see our guides to black stool and the Bristol stool chart.
This article is for general educational purposes and is not medical advice. It cannot tell you why your stool is pale, and it does not replace liver tests or imaging. Talk to a qualified healthcare professional before changing any treatment, particularly if you are pregnant, immunocompromised, taking prescription medication, or managing a diagnosed condition.
Frequently Asked Questions
What is clay-colored stool called?
Clinicians call it acholic stool, meaning stool without bile pigment. A StatPearls chapter on biliary obstruction explains that when bilirubin cannot reach the intestinal tract, stool turns pale, and that this usually appears together with jaundice and dark urine. Pale, gray, white and putty-colored are used for the same finding. The term describes what you see, not a diagnosis, so the next step is finding out why bile is not reaching the intestine.
What are the symptoms of bile acid deficiency?
When bile acids are missing or blocked, StatPearls lists pruritus (itching), dark urine, pale stools and steatorrhea (fatty, pale, foul-smelling stool) as the clinical signs of cholestasis. Without bile salts the body also cannot absorb the fat-soluble vitamins A, D, E and K, so long-standing fat malabsorption can lead to deficiencies of them. Bile acid problems have several causes, so these symptoms call for liver tests rather than self-treatment.
What color is your poo with fatty liver?
Usually normal brown. The AASLD practice guidance says that in most patients nonalcoholic fatty liver disease is asymptomatic or causes only vague symptoms, and stool color is not a recognized feature of simple fatty liver. If someone with fatty liver passes clay-colored stool, the fat in the liver does not explain it on its own. A second problem, such as a gallstone in the bile duct or a medicine reaction, is worth checking with a clinician.
What does the color of my diarrhea indicate?
Pale, loose, large-volume, foul-smelling stool is the pattern of steatorrhea, which StatPearls defines as more than 7 grams of fat in the stool over 24 hours. It can come from pancreatic enzyme shortage, bile acid deficiency or small-intestine disease such as celiac disease. Clay-colored diarrhea together with yellow skin or dark urine points more toward a bile-flow problem. Either pattern that lasts more than a few days deserves a medical review.
Can antibiotics cause clay colored stool?
Rarely, and indirectly. The American College of Gastroenterology guideline on drug-induced liver injury names antimicrobials as one of the most common drug classes behind idiosyncratic liver injury in the Western world, and the injury can be cholestatic, meaning bile flow is impaired. Most people on antibiotics never develop it. If your stool turns pale or your skin turns yellow during or after a course, call the prescriber promptly instead of stopping the medicine yourself.
Can clay-colored stool go away on its own?
Sometimes, when the cause is temporary. In hepatitis A, for example, StatPearls reports that about half of patients have cholestatic symptoms including acholic stools, and the acute illness typically resolves within two months. But you cannot tell a self-limiting cause from a blocked duct by looking at the stool. MedlinePlus advises contacting a health care provider if stools are not their normal brown color for several days.
Is clay-colored stool an emergency?
Not by itself, but it becomes urgent with other signs. StatPearls describes Charcot's triad of right upper quadrant pain, fever and jaundice as the typical picture of acute cholangitis, a bile duct infection, and adds confusion or shock as signs of a more severe form. If pale stool comes with those symptoms, go to an emergency department. Pale stool alone should still be assessed within days, not weeks.
Does black poop mean liver damage?
Black stool and clay-colored stool are different signals. Clay-colored stool reflects missing bile pigment, as explained above. Black stool has other causes, and black, tarry, foul-smelling stool can mean bleeding higher in the digestive tract, so it needs its own assessment. Our black stool guide covers the harmless and serious causes and when to seek care. If you have known liver disease and notice tarry stool, seek medical advice promptly.
What could be causing black stool without blood?
Black stool without bleeding is usually a color effect rather than a bile problem. Our black stool guide lists the common non-bleeding causes, including iron supplements and bismuth medicines, and explains how to tell them from bleeding. It is a separate question from clay-colored stool, which points to missing bile rather than added pigment. A clinician can check a stool sample if the cause is unclear.
References
- Lehrer JK, Dugdale DC, A.D.A.M. Editorial team. Stools - pale or clay-colored. MedlinePlus Medical Encyclopedia, National Library of Medicine. 2024. Available at: https://medlineplus.gov/ency/article/003129.htm ↩
- Hundt M, Basit H, John S. Physiology, Bile Secretion. StatPearls [Internet]. 2022. Available at: https://www.ncbi.nlm.nih.gov/books/NBK470209/ ↩
- Azer SA, Sankararaman S. Steatorrhea. StatPearls [Internet]. 2023. Available at: https://www.ncbi.nlm.nih.gov/books/NBK541055/ ↩
- Coucke EM, Akbar H, Kahloon A, Lopez PP. Biliary Obstruction. StatPearls [Internet]. 2022. Available at: https://www.ncbi.nlm.nih.gov/books/NBK539698/ ↩
- Buxbaum JL, Abbas Fehmi SM, Sultan S, et al.. ASGE guideline on the role of endoscopy in the evaluation and management of choledocholithiasis. Gastrointestinal Endoscopy. 2019;89(6):1075-1105.e15. doi:10.1016/j.gie.2018.10.001 ↩
- Chalasani NP, Maddur H, Russo MW, Wong RJ, Reddy KR. ACG Clinical Guideline: Diagnosis and Management of Idiosyncratic Drug-Induced Liver Injury. American Journal of Gastroenterology. 2021;116(5):878-898. doi:10.14309/ajg.0000000000001259 ↩
- Girish V, Grant LM, John S. Hepatitis A. StatPearls [Internet]. 2024. Available at: https://www.ncbi.nlm.nih.gov/books/NBK459290/ ↩
- Rinella ME, Neuschwander-Tetri BA, Siddiqui MS, et al.. AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease. Hepatology. 2023;77(5):1797-1835. doi:10.1097/HEP.0000000000000323 ↩
- Bjornsson ES, Devarbhavi HC. Drug-induced cholestatic liver diseases. Hepatology. 2024;82(4):996-1015. doi:10.1097/HEP.0000000000001052 ↩
- Whitcomb DC, Buchner AM, Forsmark CE. AGA Clinical Practice Update on the Epidemiology, Evaluation, and Management of Exocrine Pancreatic Insufficiency: Expert Review. Gastroenterology. 2023;165(5):1292-1301. doi:10.1053/j.gastro.2023.07.007 ↩
- Hall B, Levy S, Dufault-Thompson K, et al.. BilR is a gut microbial enzyme that reduces bilirubin to urobilinogen. Nature Microbiology. 2024;9(1):173-184. doi:10.1038/s41564-023-01549-x ↩
- Vítek L, Tiribelli C. Gut microbiota and bilirubin metabolism: unveiling new pathways in health and disease. Trends in Molecular Medicine. 2025;31(7):591-594. doi:10.1016/j.molmed.2024.12.007 ↩
- Collins SL, Stine JG, Bisanz JE, Okafor CD, Patterson AD. Bile acids and the gut microbiota: metabolic interactions and impacts on disease. Nature Reviews Microbiology. 2023;21(4):236-247. doi:10.1038/s41579-022-00805-x ↩
- Fawaz R, Baumann U, Ekong U, et al.. Guideline for the Evaluation of Cholestatic Jaundice in Infants. Journal of Pediatric Gastroenterology and Nutrition. 2017;64(1):154-168. doi:10.1097/MPG.0000000000001334 ↩
- Tseng JJ, Lai MS, Lin MC, Fu YC. Stool color card screening for biliary atresia. Pediatrics. 2011;128(5):e1209-e1215. doi:10.1542/peds.2010-3495 ↩